From “The Xylella Saga” in Apulia (Italy): a lesson for the precautionary protection of the environment by Alice De Nuccio

Xylella Fastidiosa is a deadly plant bacterium originating from America, able to provoke the socio-ecological collapse of entire territories. Unfortunately, in 2013, it was detected – for the first time in European territory – on the olive trees of the Apulia region, the largest olive oil producer in Italy.

This post traces the long history, from the adoption of precautionary measures to their failure in the fight against the pathogen, until the recent elaboration of regenerative measures, involving different legal levels, with the purpose of drawing a small lesson not only for the other European realities recently affected by Xylella but also for the variety of risk situations to the environmental integrity of territories.

The first step: discovery

We are in Salento, the southern area of the Apulia region, also known as the “heel” of the Italian “boot”, encompassing the entire administrative area of the province of Lecce, a large part of the province of Brindisi and part of that of Taranto. Salento was a territory crossed by “red soil” and magnificent olive trees that fed economy, culture, landscape, and the identity of the communities settled there for centuries, making Apulia the largest producer of “green gold” in Italy.

In the autumn of 2013, some olive growers in the area of Gallipoli, a municipality in the province of Lecce, observed strange symptomatology in olive trees, described as Rapid Complex Dessiccation of Olive Trees (CoDiRo). This event started a series of research that led to hypothesizing a link between the symptoms observed and Xylella fastidiosa, one of the most dangerous plant bacteria in the world, arrived in Europe from America (already known to be responsible for devastating losses of grapevines in California and citrus in Brazil). In fact, by invading xylem vessels, the bacteria block the transport of water and soluble mineral nutrients and, through gradual drying, provoke the death of the plants. Unfortunately, since the host insects that usually feed on the xylem (like spittlebugs, cicadas and sharpshooters) are able to move up to 100 meters in just 12 days, it spreads in a very short time.

The second step: precaution

A few months after the detection of Xylella, the infection became a phytosanitary emergency, which required the EU to adopt emergency measures able to extirpate the pathogen and stop the spread of the disease. But, the first actions implemented, such as limitations to the movement of plants and plant products within the EU, as well as pruning measures, were not sufficiently effective. As a consequence, on 30 December 2014, the Commission requested the scientific opinion of the European Food Safety Authority (EFSA) on “the risk to plant health posed by Xylella fastidiosa in the EU territory, with the identification and evaluation of risk reduction options”.

EFSA highlighted that “the specific role of X. fastidiosa in the [CoDiRo] syndrome remains to be understood”. However, “it presents a major risk to the EU because it has the potential to cause disease in the risk assessment area once it establishes, as hosts are present and the environmental conditions are favourable”. In particular, “the probability of entry for plants for planting from countries where X. fastidiosa is reported is rated very likely”.

On the basis of the EFSA assessment, the Commission adopted the Decision 2015/789/EU ordering the Italian competent authority – the Apulia Region – to remove all infected plants, all plants showing symptoms indicating possible infection by the organism or suspected to be infected by that organism and all host plants, regardless of their health status, within a radius of 100 meters around the infected plants. The EU Commission acted in accordance with the precautionary principle, that is one of the founding principles of the EU policy on the environment. In fact, as clarified by the Commission, it requires the adoption of a number of measures to manage a socially “unacceptable” risk to the environment, human animal or plant health, identified by a preliminary objective scientific assessment.

However, as often happens when decisions are taken in situations of uncertainty, one part of civil society strongly debated the Commission’s measures, including before the court. In particular, in parallel with the EFSA assessment, local entrepreneurs and environmental associations built a “concurrence of causes”, involving additional biotic and abiotic etiological factors (such as fungi, insects, the microbiological state of soils weakened by the use of herbicides), but also other complex ecological, political, legal, economic and social factors, and they proposed several solutions to deal with them. In 2016, the Court of Justice of the European Union (CJUE), referred for a preliminary ruling by the Tribunale Amministrativo Regionale del Lazio (Regional Administrative Court, Lazio, Italy) in landowner’s actions, confirmed the validity of the eradication measures contained in the Decision 2015/789/EU.

In the same year, as the widespread of Xylella made its eradication impossible, the Commission decided to amend its own decision by establishing “containment” rather than “eradication” measures for infected territories. These measures include monitoring the territory concerned and immediately removing only the infected plants situated, in particular, in a strip of the infected zone having a width of 20 km measured from the external border of that zone.

Despite the mitigation measures, as confirmed by the CJUE in 2019, Italy failed to comply with its obligations under the Commission’s decision, justifying itself with “various practical, administrative and legal obstacles”, such as the proper identification of some of the landowners concerned by the measures, the actions brought by a number of local farmers, which prevented the authorities from “immediately” intervening and, finally, an ongoing “national campaign of misinformation” on Xylella.

The third step: regeneration

With the Decree No. 1785/2019 by the Ministry of Agriculture, Food and Forestry (Mipaaf), Italy approved the Action Plan to relaunch the agriculture and agri-food sector in the territories affected by Xylella. It acknowledged the impossibility for the only regional institution to manage extensively on the territory the interventions to fight the bacterium. Therefore, it highlighted the need to activate greater involvement of both local administrations (municipalities, provinces and/or metropolitan cities) and private local subjects, such as associations, Local Action Groups, producer organizations etc. One of the main priorities of the plan was “to restore the productive potential” of the infected areas, not only through the removal of dead plants and replanting of resistant olive cultivars, but also the conversion to other crops.

On this line, with the Inter-ministerial Decree No. 7775/2019, the Ministry for agricultural politics (“Mipaaf”), jointly with the Ministry of Economic Development, regulated the “Xylella district contracts”: contracts concluded between the Mipaaf and the “food districts” (i.e. territorial production systems composed of enterprises operating in the same territory and cooperating on the basis of an agreement), with the aim of carrying out a program for the agriculture regeneration in the areas affected by the bacterium through the financing of the projects included therein.

In 2021, the Mipaaf approved the first Program of “Sustainable Regeneration” presented by Distretto Agroalimentare di Qualità Jonico Salentino (DJAS), a food district that brings together 187 enterprises, including 78 public and private subjects, 7 research institutes and universities. One of the most interesting activities of the Program is the proposal for “productive forestry” of the affected areas. It is a research project concerning the creation of a renaturalized system, which should replace the ecological network provided by the extensive cultivation of olive trees with a wood areas network, connecting municipalities and provinces of Salento. The activity involves the main Apulian research institutes and universities, the Apulia Region, Province and Municipalities of the area willing “to face the challenge by sharing the path with the communities of Salento”.

The regeneration path includes: the census and identification of abandoned or semi-abandoned areas suitable for forestry, marginal areas and the definition of precise geographical and administrative boundaries; the identification of the most fitting species for reforestation, calculating their carbon sequestration capacity; the definition of a “post-forestry” policy for the enhancement of forest systems according to the most virtuous principles of the circular economy (building and/or lengthening the production chain in the sector, creating models of administrative “public procurements” that consider the “Km zero” wood of Salento; enhancing “ecosystem services” produced by the forest systems).


The Xylella Saga is not an end in itself but has a “moral story” for the other EU cases of infection by the bacterium (France, Spain, Portugal) and, in general, all risk situations for the environmental integrity.

In the specific case, the precautionary principle failed not because of its inherent inability to protect the environment, but for an excess of application rigidity, both from the procedural and organizational perspective. In fact, its operational structure has some limitations: it is punctuated by a “risk assessment” phase (EFSA assessment), a “risk management” phase (Decision 2015/789/EU) and a “risk communication” phase. It is likely that, as a result of closely following this logical order (in particular, the public involvement only to receive uncritically the information on a decision taken “behind closed doors”), the Commission’s decision did not dissolve the conflict between interests, value choices, rules of scientists, administrations, civil society, paralyzing the precautionary action.

On the contrary, once the damage occurred, Italy recognized the need for a widespread involvement of public and private subjects at all levels in order to gather the sufficient strength to restore it. And so, for example, the active participation of a plurality of scientists, administrations, members of civil society developed a completely innovative significance of “regeneration” that does not mean “restoration” of the previous ecological balance, but it also considers the possibility of creating new ecosystems and balances.

If this adaptive method had been applied at the precautionary step, perhaps, a different but more effective decision could have been reached.

In essence, in an attempt to draw a general conclusion, the Xylella Saga testifies that the environmental law fails to fulfil its duty of protection when, it does not apply the principle of subsidiarity, both in its vertical dimension, by acting in co-administration at various levels, and in its horizontal dimension, by involving civil society in decision-making. Subsidiarity, therefore, in addition to being a fundamental principle for the precautionary principle functionality is, first of all, an expression of the necessary procedural and organizational adaptation to environmental emergencies.

Alice De Nuccio is a PhD student and pre-doctoral contract researcher at the University of Santiago de Compostela (Spain), where she carries out teaching and research activities. Her PhD thesis analyses the legal instruments to combat rural depopulation, comparing the Spanish and the Italian legal systems. Alice’s interests also include other topics of study from environmental law, agri-food law and administrative law. She studied at the University of Salento (Italy), where she got a master in law with a dissertation on the evolutionary profiles of the precautionary principle in environmental law. Alice has been a Visiting PhD Student at the Scuola Superiore Sant’Anna in Pisa, the University of Heidelberg and the University of Florida.

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